Tubular covering and method



Aug. 15, 1967 R. L. HATTON TUBULAR COVERING AND METHOD Filed June 17,1965 INVENTOR;

RICHARD L. HATTON United States Patent 3,336,554 TUBULAR COVERING ANDMETHOD Richard L. Hatton, Elmhurst, Ill., assignor to ResiniteCorporation, Wheeling, 11]., a corporation of Illinois Filed June 17,1965, Ser. No. 464,708 Claims. (Cl. 336-209) This invention relates to atubular covering and method and, more particularly, to a covering forelectronic elements such as coils.

It is particularly important to protect electronic elements such ascoils against dust, moisture, corrosive effects in general, fungus, etc.Therefore, coils have been equipped with protective coverings, and forthat matter, so have a variety of difierent tubular elements. Theprovision of a useful tubular covering-as for the protection outlinedabove-constitutes an object of this invention and further, the coveringis one that is constructed and installed in an unexpectedly facilemanner.

The invention is explained in conjunction with an illustrativeembodiment in the accompanying drawing, in which:

FIG. 1 is a perspective view of a delay line coil equipped with theinventive protective covering;

FIG. 2 is an exploded perspective view of the structure of FIG. 1, butin a stage of manufacture prior to that shown in FIG. 1;

FIG. 3 is an enlarged sectional view taken along the line 3-3 of FIG. 1;and

FIG. 4 is an enlarged fragmentary sectional view taken along the line 44of FIG. 3.

In the illustration given and with particular reference to FIG. 1, thenumeral designates generally a delay line coil which includes a coilform or rigid tubular support 11 (see also FIG. 4) on which is wound aplurality of convolutions or turns of conductor wire 12. The ends of theform 11 are equipped with lugs 13 for establishing electricalconnections with the wire windings 12. Overlaying the winding 12 betweenthe spaced-apart lugs 13 is a tubular covering generally designated 14and which can be seen in perspective view in FIG. 2. The covering 14includes an inner layer 15 and an outer layer 16 (see FIG. 4) which areconstructed of resilient plastic film adhesively united. As can beappreciated from FIG. 2, both layers are spirally wound, the spiralWinding of the layer 16 being developed by abutting edges as at 17 whilethe spiral winding of the inner layer 15 develops butted edges as at 18.The edges 17 and 18 are spaced apart, i.e., the convolutions of thewinding 16 overlap the convolutions of the wound layer 15.

As seen in FIG. 2, the covering 14 is longitudinally slit as at 19 and Ihave found that when the layers 15 and 16 are constructed with the layer16 slightly thicker than the layer 15, the slit covering 14 tends toform a tight cylinder so as to clamp and envelop the coil form 11 as at20 in FIG. 3.

As an example of the practice of the invention, I spirally wind a 0.00thick ribbon of cellulose acetate to provide the inner layer 15 andsuperpose an offset spirally wound condition a layer 16 of 0.003" thickcellulose acetate. A small amount of acetone is introduced between thelayers 15 and 16 causing them to adhere. The thickness of the spirallywound double layered tube thus developed is arranged to be slightlylarger than the diameter of the delay line coil to be covered.Thereafter, the tubular covering is longitudinally slit and flexed,i.e., manipulated as at 21 and 22 to open the same for enveloping thecoil form 11. Thereafter, the flexing pressure at 21 and 22 is releasedwhereupon the edges of the slit 19 snap together in the overlappedfashion indicated at 20 in FIG. 3. In some instances, I find that thecovering can be further advantageously stabilized by introducing acetonebetween the overlapped portions 20a and 20b to effect a union or afusing of the two overlapped portions.

A variety of materials of construction may be employed for the layers 15and 16. Cellulose acetate, as illustrated above, is advantageous becauseof its low cost and ready fusibility using a common solvent, acetone.However, other resilient plastic film such as ethylene terephthalate mayalso be advantageously employed. It will also be appreciated that theinner and outer layers may be constructed of dilTerent materials, but insuch a case the thicknesses must be adjusted to develop a greater resiliency, i.e., a tendency to convolute, in the outer layer.

While in the foregoing specification, a detailed description of theembodiment of the invention has been set down to explain the invention,many variations in the details herein given may be made by those skilledin the art without departing from the spirit and scope of the invention.

I claim:

1. A tube covering comprising inner and outer layers of resilientplastic film, each layer being spirally wound relative to the axis ofsaid tube, the spiral winding in one layer being offset axially from thespiral winding in the other layer, said layers being adhesively unitedwith the outer layer being thicker than the inner layer, said coveringbeing relatively elongated and longitudinally slit.

2. The covering of claim 1 in which said layers are of the order of afew thousandths of an inch in thickness.

3. An electrical element comprising a wire wound tube form, and acovering thereon, said covering comprising resilient inner and outereach layer being spirally wound relative to the axis of said tube, thespiral winding in one layer being offset axially from the spiral windingin the other layer, said layers being adhesively united with the outerlayer being thicker than the inner layer.

4. A method of covering a tubular element comprising spirally windinginner and outer layers of flexible plastic film to form a unitary tubewherein the layer spirals are offset and with the outer layer beingthicker than the inner layer, longitudinally slitting said tube, flexingthe same transversely to position said slit tube in enveloping relationwith said element, and releasing said tube to cause the same to contractinto contacting relation with said element.

5. The method of claim 4 in which the longitudinal edges of said tubeadjacent the slit or overlap are fused subsequent to said releasing.

LEWIS H. MYERS, Primary Examiner. T. J. KOZMA, Assistant Examiner.

layers of resilient plastic film,

3. AN ELECTRICAL ELEMENT COMPRISING A WIRE WOUND TUBE FORM, AND ACOVERING THEREON, SAID COVERING COMPRISING RESILIENT INNER AND OUTERLAYERS OF RESILIENT PLASTIC FILM, EACH LAYER BEING SPIRALLY WOUNDRELATIVE TO THE AXIS OF SAID TUBE, THE SPIRAL WINDING IN ONE LAYER BEINGOFFSET AXIALLY FROM THE SPIRAL WINDING IN THE OTHER LAYER, SAID LAYERSBEING ADHESIVELY UNITED WITH THE OUTER LAYER BEING THICKER THAN THEINNER LAYER.